Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) - Southern California Edison - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	$ 2,810	$ 2,917
Fair Value	4,344	4,331
Stocks
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	329	304
Fair Value	1,488	1,460
Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	675	691
Fair Value	854	840
U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	1,002	1,070
Fair Value	1,107	1,128
Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	683	708
Fair Value	771	755
Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	121	144
Fair Value	124	148
Repurchase agreement	$ 85	$ 81